Note: Descriptions are shown in the official language in which they were submitted.
~5~692 :
This invention pertain~ to a composition con~
taining an epoxy resin and a lat:ent catalyst for promo-
ting reaction between vicinal epoxides and phenols and/-
or carboxylic acids (or anhydricles o~ such acids~, and
the process of reacting an epoxy compound with a phenol,
carboxylic acid, anhydride, or a mixture thereof. Such
reactions are commercially important in that functional
monomers (e~g. hydroxyethyl acrylate), hydraulic fluids
~e.g. 2-phenoxyethanol) and high molecular weight linear
or cross-linked epoxy resins are thus produced.
The reactions between epoxides and phenols
and/or carboxylic acids (or anhydrides) have been ex-
tensively studied and many patents have issued which
describe these well known classes of reactants. See,
for example, U.S. Patents:
2,216,099 3,377,406 3,547,885 `
2,633,458 3,477,990 3~694,407 `
;i, .
2,65~,885 3,547,881 3,738,862
Canadian patent 893,191, German patent DT 2,206,218, ;~
and the tex~ "Handbook of Epoxy Resins" by H. Lee and
K.Neville, McGraw Hill, N.Y. (1967).
In addition to describing the classes of re-
actants, the above patents also show that (1) a catalyst
is re~uired to attain a saticfactory reaction rate and
(2) those skilled in the art recognize that the reaction
between epoxides and phenols is not, mechanistically
,
speaking, the same as the reaction between epoxides and
carboxylic acids (or anhydride) due to the differences
in products. The latter point is illustrated by ~he
fact that substantially linear polymers are produced
1/,312-F "B" -1-
3 ~35969Z :
(U.S. Patent 3,477,990) by reacting epoxy resins with
polyfunctional phenols in the presence of a catalyst
whereas cross-linked polymers are produced (U.S. Pat-
ent 3,547,885~ by reacting the same epoxy resins with
a polycarboxylic acid (or anhydride) in the presence
of the same catalysts. The reactive species which cata-
lyze~ the reaction is therefore believed to be different
in each instance. Thus, compounds which catalyze one
reaction would not necessarily be expected to catalyze
the other.
Several problems have been enco~ tered in us-
ing many of the prior art catalysts. In many instances,
the catalysts react with the epoxy reactant and thus pre-
clude the option of marketing a blend comprising an epo-
xy re3in and a catalyst; this blend is commonly referred
to a~ a "precatalyzed epoxy resin". In other instances,
the problem associated with the prior art catalysts is
selectivity; i.e. the catalyst simultaneously promote the
reaction between the epoxy reactant and the phenolic hy- -
droxyl group (or acid group) on the reactant and the ali-
phatic hydroxyl ~roup(s) on the product giving branched ^~
or cross-linked polymers rathsr than the desired linear
polymers. In skill other instances, the reaction rate
is unsatisfactory and/or the product is highly colored
and therefore unsatisfactory for many uses and/or the
product was contaminated with corrosive anions (e.g~
chloride) and is therefore unacceptable for electrical
encapsulation ~potting)~
It has now been found that certain phosphonium
salts ~re novel latent catalyst~ for promoting the reaction
1^/,312-F "B" -2-
~ - \
~5969Z :
between vicinal epoxides and phenols and/or carboxylic
acids (or anhydrides).
The catalysts are surprisingly effective in
selectively catalyzing the desired reaction between the
reactants at a suikable reaction rate. The reaction
products are obtained in high yields and are of generally
excellent color.
Additionally, the catalysts are surprislngly
unreactive with epoxy resins at conventional storage tem-
peratures. As a result, precatalyæed epoxy resins can ;
now be produced by merely blending the subiect catalysts
with the epoxy resins. Such precatalyzed epoxy resins
are, of course, novel compositions of matter.
The present invention accordingly provides a pro-
cess which comprises reacting (a) a vicinal epoxy group-
-containing compound with (b) a phenol, a carboxylic acid,
a carboxylic acid anhydride, or a mixture thereof in pre- -
sence of a phosphonium salt corresponding to the formula
., ~ .
p - R2 A~
OH
wherein Rl-R3 are hydrocarbyl or inertly-sub3tituted hy-
drocarbyl radicals, each of which independently has from
1 to about 20 carbon atoms, preferably each n-butyl or
phenyl and most preferably n-butyl; R4 is hydrogen, benzyl
or lower alkyl (1 to 6 carbon atoms); and A~ is a compa-
tible neutralizing anion (such as chloride, bromide, io-
dide, bisulfate, chlorosulfonate, acetate, diacetate,
' .
~"
1 7 ~ 312-F "B"
:~ .
04
1~59~;9Z ~,
tri1uoromethylsulfonate, trifluoroacetate, toluenesul-
fonate, nitrate, adipate, acrylate, chloroacetate, or
trichloroacetate). The non-nuclaophilic anions (such as
bisulfate, acetate, chloroacetate, diacetate or adipate)
are preferred anions for precatalyzed resins. Bromide
and iodide anions are the preferred nucleophilic anions.
Rl-R3 are likewise preferably each n-butyl or phenyl and
are most preferably n-butyl. R~ is preferably hydrogen.
The invention further provides a composition -
containing an epoxy resin and a phosphonium salt as defined ~ '
above, which may also contain, in addition, a ph~nol, a
carboxylic acid, a carboxylic acid anhydride, or a mix-
ture thereof.
The phosphonium salts can be prepared by reac-
ting an inner salt corresponding to the formula
d3 .. .
~ P R2
OH
with a Br~nsted acid (~A~) or with an alkyl or benzyl
chloride or bromide. The anion of any particular salt
can be exchanged for another anion by conventional anion
exchange techniques.
The inner salt intermediates can be prepared
by reacting 1,4-benzoquinone with a tertiary phosphine
(P-R12 in an inert solvent (e.g. benzene) and filtering
off ~he product.
Illustrative examples of the present class of
catalysts include those of the above formula wherein Rl-R3
1~,312-F "B" -4- ~
~5g~92 :
are Cl 20 alkyl such as methyl, ethyl, n-butyl, hexyl,
oxtyl, decyl, dodecyl, or octadecyl; phenyl; alkyl
(Cl 8) phenyl such as tolyl, 4-octylphenyl, or 3,5-
-dimethylphenyl; phenyl-lower alkyl such as benzyl,
phenethyl phenylbutyl, or 3,5-dimethylbenzyl; cyclo-
alkyl such as cyclohexyl; lower alkenyl such as allyl;
hydroxyloweralkyl such as hydroxymethyl; cyano-lower
alkyl such as cyanoethyl, or 2-cyanopropyl, wherein
the lower alkyl groups contain from 1 to 6 carbon atoms~
Other illustrative examples inc].ude those in which Rl-
-R3 are different. For example, those in which R1 is
n-butyl, R2 is phenyl and R3 is phenyl; those in which
Rl is hexyl, R2 is tolyl, and R3 is benzyl; and other -
like variations.
The above phosphonium salts are particularly - -
useful in catalyzing the reaction between vicinal epoxides
and phenols and/or carboxylic acids. In this utility,
the amount used can be varied over a wide range. Gen- -erally, however, they are used in a small but catalytic
amount, as for example in amounts of from about 0~001 to
about 10 percent by weight, based on the combined weight
of reactants. Preferably, the catalyst is included in
amounts of from about 0~05 to about 5 percent by weight.
As stated above, the reactants are well
, . .
known classes of compounds.
The vicinal epoxides, for example, are organic
compounds bearing one or more -~-C- groups. The alkylene
oxides of from 2 to about 24 carbon atoms, the epihalo-
hydrins and the epoxy resins are perhaps the best known
and most widely used members of the genus. ~thylene
:
17,312-F "B" -5-
3L~5969~
oxide, 1,2-propylene oxide, 1,2-butylene oxide and epi-
chlorohydrin are the preferred monoepoxides. There are
two preferred subclasses of epoxy resins. The first
subclass corresponds to the general formula
`~
O-C~2-C~ 2 O-CH2-CH-CI:21 0-C~12-C~-\C~
R ~ CH ~ l CH2
1 0
wherein R is hydrogen or an alkyl radical and n is from
about 0.1 to about 10, preferably from about 1 to about
2. Preparation of these polyepoxides is illustrated
in U.S. Patents 2,216,099 and 2,658~885. The second
subclass corresponds to the general formula -
~ .
CH2\CH-CH2-O- ~ - A - ~ - O-CH -CH\CH ~
R2
~;
wherein R, Rl, R2 and R3 are independently selected from
hydrogen, bromine and chlorine and wherein A is an al-
kylene (e.g. methylene) or alkylidene (e.g. isopropyli-
dene) group having from about 1 to about 4 carbon atoms,
-S-, -S-S , -SO , -SO2-, -CO-, or -O-.
The phenols are organic compounds having one
or more hydroxyl groups attached to an aromatic nucleus.
This class of compounds therefore includes phenol, alpha
and beta-naphthol, o-, m-, or ~-chlorophenol, alkylated
derivatives of phenol (e.g. o-methyl-, 3,5-dimethyl-,
',;
17,312-F "B" -6- ~
:.
~L~59692
p~t-butyl- and ~-nonylphenol) and other monohydric phe-
nols as well as polyhydric phenols, such as resorcinol
or hydroquinone. The polyhydric phenol~ bearing from
2 to 6 hydroxyl groups and having from 6 to about 30
carbon atoms are particularly useful in the reaction
with epoxy resins to ~orm high molecular weight re~ins
(linear or cross-linked) useful in coatings. Particularly
preferred polyhydric phenols are those corresponding to
the formula
. ... .. .
R R R R ;~:
HO-- ~--X--~--OH
~;
. .
R R R R ~ -
wherein R is hydrogen, halogen (fluoro, chloro or bromo)
or hydrocarbyl and X is oxygen, sulfur, -SO-, -SO2-, bi-
valent hydrocarbon radicals containing up to 10 carbon
atoms, and oxygen, sulfur and nitrogen-containing hydro-
carbon radicals, such as -OR'O-, -OR'OR'O-, -S-R'-S-,
-, i
-S-R'-S-R'-S-, -OSiO-, -OSiOSiO~, -O-C-R'-C-O-,
' O o o o .: ,
.. " " " ~ .
-C-O-R'-O-C-, -S-R'-S- and -SO2-R'-SO2- radicals wherein
R' is a bivalent hydrocarbon radical. 4,4'-I opropyli-
denediphenol (i.e. bi~phenol A~ is the most preferr~d '
phenol).
The organic carboxylic acids and anhydride~
are likewise well known. The acids bear one or more
carboxyl groups on the organic nucleus. The anhydrides `-
are prepared from such carboxylic acids by the removal
of water therefrom in an intra- or intermolecular
17,312-F "B" -7-
~ . .. . . .. .
lOS969;2 ;
'::
condensation. This class of compounds therefore in-
cludes acetic, propionic, octanoic, stearic, acrylic,
methacrylic, oleic, benzoic, phthalic, isophthalic,
maleic, succinic, adipic, itaconic, polyacrylic and
polymathacrylic acids, and anhydrides thereof, such
as acetic anhydride, phthalic anhydride, or hexahy-
drophthalic anhydride.
There are two subclasses of carboxylic acids
and anhydrides that are particularly important ba~ed
on their reaction with epoxy resins.
The reaction of ethylenically unsaturated
monocarboxylic acids with epoxy resins produces hy-
droxy-substituted esters or polyesters which are par-
ticularly useful in the preparation of coatings, ad-
hesives, etc. See, for example, U.S. Patant 3,377,406.
Acrylic and methacrylic acid are particularly useful
in this regard. Accordingly, the ethylenically unsa-
turated monocarboxylic acids are a preferred subclass
of acids.
The second preferred subclass of acids is com-
pri~ed of members which are useful in cross-linking `~
epoxy resins. The members of this subclass are nor-
mally di- or tribasic acidsf or anhydrides thereof,
and are preferably liquid or low-melting solids, such
as succinic, maleic or hexahydrophthalic acids or an-
hydrides. Other such acids and anhydrides are shown,
for example, in U.S. Patent 2,970,983 and U.S. Patent
3,547,885.
The ratio of vicinal epoxide reactant to phenol
and/or carboxylic acid reactant in the subject process
17,312-F "B" -8~
- - . . . . .~ - :
. . ~ , , .
1~5969'~
can vary over a wide range depending upon the product
desiredO E.g. if a product terminated with a phenolic
ether group is desired, obviously one would employ an
excess of phenol in the process.
In many in~tances the xeactant~ are liquid
and no solvent or diluent is needed. In other cases,
however, where one or both of the reactants are solid
or viscous liquids, an inart solvent or diluent can
be used advantageously. Suitable such inert solvents
or diluents are known to those skilled in the art and
include ketones (such as acetone or methyl ethyl ke-
tone), hydrocarbons tsuch as benzene, toluene, xylene, -
cyclohexane, or ligroin).
Generally, the reaction mixture is warmed at
temperatures in the range of from about 50C to about `
225C (preferably 100-175C) until an exotherm begins ~ -
and, after the exotherm has peaked, substantially
warmed in the same range ~or an additional time to
assure substantially complete xeaction. Atmosphe-
ric or superatmospheric pressure (e.g. up to about
200 psig (1~ kg./cm.2 guage)) are common.
The products produced are generally known
~:
compounds in industry. The particular product pro- ;
.. ; ,. . .
duced will vary in properties depending upon the
selection and ratio of reactants used in the process.
The following discussion will illustrate the types of
products which can be produced.
The products produced by reacting an epoxy
resin with a phenol in the pre~ence of the subject
catalysts are phenolic ethers bearing one or more
'
17,312-F "B"
~l~59~;92
aliphatic secondary hydroxyl groups. Such aliphatic
hydroxyl groups axe formed in the ring-opening reac-
tion between the oxirane and phe.nolic hydroxyl groups.
Additionally, the reaction products bear a termlnal
epoxy group(s) or a phenolic hydroxyl group (8) depen- ;
ding upon the ratio of xeactants. Consequ~ntly, they are
reactive intermediates which can be cured (cross-
-linked) with many polyfunctional curing agents to
form hard, insoluble solids which are useful coatings.
A list of several known curing agents which are suit-
able for use herein is found in U.S. Patent 3,477,990.
The cured products (particularly those of high mole-
cular weight) are useful as surface coatings, as ad-
hesive lay~rs in laminates, coatings on filament wind-
ings, or in structural binding applications. The prod- ;
ucts prepared from halogenated (particularly bromina-
ted) phenols are particularly useful in flameproofing
applications, since they tend to be self-extinguishing.
Thus, they are useful in forming cured coatings for wood
paneling and as adhesive layers in wood laminates.
The products produced by reacting an epoxy
resin with a monocarboxylic acid (or anhydride of such
acids) have terminal ester groups and are useful in
coatings, adhesives, reinforced plastics, or moldings.
The products formed by reacting epoxy resins with poly-
carboxylic acids, or anhydrides thereof, a~e cross-
-linked insoluble resins useful in coatings.
Functional monomers are produced by reacting
a C2 to C4 alkylene oxide with acrylic or methacrylic ~:~
acid. Hydraulic fluids are prepared by reacting a lower
17,312-F "B'~ -10-
~596~t2
alkylene oxide with a phenol in substa~tially equi-
molar amounts. Nonionic surfactants are prepared
by reacting an alkylated monohydric phenol with a
C2 to C4 alkylene oxide, or mixture of such alkylene
oxides.
Other useful products can be similarly
prepared by the reaction of vicinal epoxides with
phenols and/or carboxylic acids (or anhydrides)
in the pr~sence of the subject catalysts. ~ -
The following examples further illustrate
the invention:
Examples 1-5
This series of experiments was conducted by
charging to a reaction vessel (equipped with a ther-
mometer and mechanical stirrer and prepurged with ni-
trogen) a diglycidyl ether of bisphenol A having an ~
epoxy equivalent weight of 187 (4.5 g.), bisphenol A ;-
(2.628 g.) and 0.011 g. of the phosphonium catalyst
dissolved in methanol. The reaction mixture was warmed
up to about 150C after which the heat was turned off.
An exotherm was observed in each instance and after
the exotherm subsided, the reaction mixture was heated
at 160C for an additional 3 hours. The results of
the experiments are shown in Table l. All o~ the re-
sins produced were of excellent color.
.,
. .
17,312-F "B" ~
1~59Çi9~
TABLE I
c eening ~esults to Prepare
L1near ~ ~ r ~ai ht ~p ns
Theo- Actual %
retical Epoxide
Percent Remain-
Example ~ y~ Epoxide in~
F2H5 ~ I~ 2.00 2.05
P-(C6H5)3
OH
2 O,H ~ HS04~ 2.00 2.94 -.
~P-~C6H5)3
O ~,
3 O~ 0 ~O-C-CH3 2.00 2.04
~P--(C6H5)3
0~1 `,
~."
4 ~ P-(C6H5)3 3 3 2.85
OH
P-~C~H5)3 Br 2.00 2.20
O
Examples 6-10
This series of experiments was conducted in an .
analogous fashion except that 2~812 g. of bisphenol A .
was used in each instance and the reaction mixtures were '
heated at 160C fvr 5 hours ins~ead of ~he 3 hours~u~ed
above. The results are summarized in Table II.
'~
'''"~ '
17,312-F "B" -12- ~ .
~L~596~2
TABLE II
Epoxy Catalyst Screening Results to Pre are
Llnear Hig Molecular Wei ~
Theo- Actual %
retical Epoxide
Percent Remain-
Example Catal~st ~oxide ing
6 OC2Hs ~ ~ 1.00 1.26
--P--(C6H5)3
OH
,
7 OH ~ HSO ~ 1.00 2.47
~ -P-(C6H5)3 4 `
O '`''
8 O,H ~ ~ " 1.00 1.20 ;-
-P-(C6H5)3 O-C CH3
OH `'
9 ~ -P-(C6H5)33 ~ CH3 2.37
OH
O~ ~ B ~ 1.00 1.36
1~1--P--(C6H5) 3
0
Examples 11-23 '.
This series of experiments was conducted in ;~
analogous fashion except that 1.698 gO of bisphenol A
was used in each instance and the reaction mixtures were
heated at 160C for only 1.5 hours instead of the times .
u3ed heretofore. The results are summarized in Table
III. ,,
17,312-F "B" -13- ~
- ~.,. . . . , . ~ , , ~ .. . . . . . . .
~596'~2
TABLE III
Epoxy Catalyst Screening Results to Pre~Pare
Linear Hiqh Molecular Weiaht EPoxv Reslns
- -- ...... ~ ~
Theo- Actual %
retical Epoxide
Percent Remain-
Example Catalyst ~ ing .
11 ~C2Hs ~ ~ 8.20 8728
(C6H5)3
H
12 OH ~ Cl~ 8.20 8.31
~ -P-(C6H5)3
OH
13 ~O ~ 8.00 7.65
4H9)3 ~-;
~ CF3C2(~) ,
14 ~O ~ 8.00 7.95
-P~nC4Hg)3
HO ClCH2C02(~)
. ,~ .
HO ~ 8.00 8.09 .
~P~n-C4Hg)3
HO CH2=CH-CO2a .
16 HO ~ 8.00 8.29
~n C4Hg)3
HO ~O2c~cH2~4cO~H ;
17 ~O 63 8.00 7.94 ,.
~ P (C6H5)3 ;,;~.
~0 CF3C02~3
`j.:; . .
18 HO ~ 8.00 8.58
(C6H5)3
~o No3~3 ;~ :
17,312-F "B" -14- ~
~.~59~9Z
TABLE III (Continued)
Epoxy Catalyst Screening Results to Prepare
Llnear High Molecular Wei~ht Epox~ Resins
Theo- Actual ~ ~
retical Epoxide : .
Percent Remain~ -
Exam~l~ ~ Epoxide ing -:
19 ~0 63 CH2=CH-CO2~ 8~00 8.27
( 6H5)3
HO ,,~
.
~O G3 8.00 8.21
. ~ ( 6 5)3 `
HO CLCH2CO
21 ~O ~ 8.00 8.06
(C6H5)3
HO C13CC02~3
22 ~O ~ 8.00 7.62
(~--P E~CH2t9CH3] 3 , ~
~0 ~O-C-CF3 ..
O ,.
23 HO ~ 8~00 7.65 ::
~ -P~CH2CH2CN)3 ,
,l 3 ,
O '',
The foregoing examples demonstrate that the
present catalysts are particularly good latent catalysts
for promoting the reaction between epoxy resins and
phenols.
Exam~les 24-27 :.
In this series of experiments a diglycidyl
ether of bisphenol A having an epoxy equivalent weight
17,312-F "B" -15-
~5~69;~
of 172-178 (100.0 g.) and hexahydrophthalic anhydride
(80.0 g.) and the catalyst ~0.15 g.) were thoroughly
mixed and maintained under a vacuum for at least 15
minutes or until bubbling under vacuum was very slight.
The reaction mixture was then warmed at 110C for 2
hours, the heat turned off and the exotherm allowed to
subside. The reaction mixture was then heated at 150C
for an additional 2 hours and cooled. In every in-
stance, ~he cured product was clear, colorless and
very hard. The catalysts are described in Table IV.
TABLE IV
Catal st Screening Results to Cross-Link ~-
E~oxy Resins with_A_hydrides
Exam~le ~ y~
24 OH 63 HSO ~3
I~l--P- tC6H5) 3
OH
O ..
~ -P-(C6H5)3 3
HO ~
' `
26 CH3CH2~, ~3
~ (C6H5)3
H
27 ~ -P-(C6H5) 3 ~ 3
;~
' .: ,
In a companion series of experiments, aliquots
of the above mixtures were maintained for t~o weeks at
room temperature prior to curing and no appreciable
:
change in the viscosity of the uncured mixtures was
noted.
.. " , .
17,312-F "B" -16~
~ ~:35969Z
Similar good results were noted in another
series of expariments wherein the hexahydrophthalic
anhydride used in the above formulations was replaced
with dodecenyl succinic and nadic methyl anhydrides,
but longer cure schedules were required.
The cured products from the above examples
strongly adhered to the reaction vessel and were use-
ful as protective coatings~
Modifications of the above experiments can
be made. For example, the above anhydrides can be -
replaced with other anhydrides such as maleic anhydride
leading to cross-linked products. Alternatively, acry-
lic or methacrylic acid could be used in the reaction
conditions leading the epoxy resins terminated with a
free-radical or thermally polymerizable vinyl groups.
Sucù comoounds are likewise usetul Is ooating materials.
"~
:'
.
17,312~F "B" -17-
